This invention relates to the running and freeing of stuck or jammed tubulars downhole without the use of overhead tubular and oscillator support structure, using eccentric weight mechanical oscillators. More particularly, the invention includes a snubbing-type jack and an oscillator apparatus having a central tubular stem for accommodating tubulars and designed to utilize resonant frequency vibration in combination with the snubbing-type for freeing tubulars such as drill pipe, casing and other jointed tubulars, as well as continuous or coiled tubing in the well. Freeing of the coiled tubing or other tubulars in the well by typically resonance vibration is effected when the coiled tubing or alternative tubular has been clamped to the oscillator and isolated from the jack. In a first embodiment the oscillator/snubbing jack combination operates to run jointed tubulars in a well and free stuck downhole members by selectively transferring the tubular load from the snubbing jack to the oscillator and operating the oscillator to vibrate and free the tubular load in the well. In a second embodiment the apparatus is modified to run coiled tubing from a reel by adding a xe2x80x9cgooseneckxe2x80x9d coiled tubing guide and a coiled tubing injector and for guiding the coiled tubing through a central stem of the oscillator and through the injector, into and from the well.
Oil field tubulars such as well liners, casing, tubing and drill pipe which become stuck in a well bore due to various downhole conditions have been one of the principal sources of problems for oil operators and have expanded the business activity of fishing service companies in this century. During this period of time, many new and innovative tools and procedures have been developed to improve the success and efficiency of fishing operations. Apparatus such as electric line free point tools, string shot assisted backoff, downhole jarring tools, hydraulic-actuated tools of various types and various other tools and equipment have been developed for the purpose of freeing stuck or jammed tubulars downhole in a well. Although use of this equipment has become more efficient with time, the escalation in cost of drilling and workover operations has resulted in a proliferation of stuck pipe, liners, casing, and like tubulars downhole, frequently leading to well abandonment as the most expedient resolution of the problem.
The use of vibration, and resonant vibration in particular, as a means of freeing stuck tubulars in a well bore has the potential to be immediately effective and thus greatly and drastically reduce the cost involved in tubular recovery operations. Resonance occurs in vibration when the frequency of the excitation force is equal to the natural frequency of the system. When this happens, the amplitude (or stroke) of vibration will increase without bound and is governed only by the degree of damping present in the system.
A resonant vibrating system will store a significant quantity of energy, much like a flywheel and the ratio of the energy stored to the energy dissipated per cycle is referred to as the systems xe2x80x9cQxe2x80x9d. A high energy level allows the system to transfer energy to a given load at an increased rate, much like an increase in voltage will allow a flashlight to burn brighter with a given bulb. Only in resonant systems will achieve this energy buildup and exhibit the corresponding efficient energy transmission characteristics which assure large energy delivery and corresponding force application to a stuck region of pipe or tubing.
Under resonant conditions, a string of pipe or tubing will transmit power over its length to a load at the opposite end, with the only loss being that necessary to overcome resistance in the form of damping or friction. In effect, power is transmitted in the same manner as the drilling process transmits rotary power to a bit, the difference being that the motion is axial translation instead of rotation. The load accepts the transmitted power as a large force acting through a small distance. Resonant vibration of pipe or tubing can deliver substantially higher sustained energy levels to a stuck tubular than any conventional method, including jarring. This achievement is due to the elimination of the need to accelerate or physically move the mass of the pipe or tubing string. Under resonant conditions, the power is applied to a vibrating string of pipe or tubing in phase with the natural movement of the pipe or tubing string.
When an elastic body is subjected to axial strain, as in the stretching of a length of pipe, the diameter of the body will contract. Similarly, when the length of pipe or tubing is compressed, its diameter will expand. Since a length of pipe or tubing undergoing vibration experiences alternate tensile and compressive forces as waves along the longitudinal axis (and therefore longitudinal strains), the pipe or tubing diameter will expand and contract in unison with the applied tensile and compressive waves. This means that for alternate moments during a vibration cycle the pipe or tubing may actually be physically free of its bond.
The term xe2x80x9cfluidizationxe2x80x9d is used to describe the action of granular particles when excited by a vibrational source of proper frequency. Under this condition, granular material is transformed into a fluidic state that offers little resistance to movement of body through the media. In effect, it takes some of the characteristics and properties of a liquid. Accordingly, skin friction, the force that confines a stuck tubular, is reduced to a small fraction of its normal value due to any unconsolidated media that may surround the tubular, tending to become fluid at the interface with the vibrating pipe. Accordingly, the vibrational energy received at the stuck area works to effect the release of a stuck tubular member through the application of large percussive forces, fluidization of granular material, dilation and contraction of the pipe or tubing body and a reduction of well bore friction or hole drag.
Snubbing units, coiled tubing units, jacks or casing jacks are typically used in well construction, completion and remedial or workover situations where there is no overhead tubular support structure, and where objects such as various tubulars may be stuck in the well bore and must be removed in order to complete the work. Additionally, the pipe work string or tubing itself may become stuck in the well bore and must be freed and recovered so that the work can continue. In either event, pipe or tubing vibration from the surface may be used as a method of recovering the stuck tubular members or the work string itself and for reducing tubular insertion and removal friction, as well as other useful purposes.
A typically resonant vibration system used in connection with snubbing-type jacks and units in oilfield tubular running and extraction applications according to this invention, consists of a mechanical oscillator mounted by means of vibration insulators, isolators or reflectors on a snubbing-type unit or jack. Under circumstances where the tubular in the well is coiled tubing, a coiled tubing injector and a xe2x80x9cgooseneckxe2x80x9d coiled tubing guide are added to this combination. The oscillator generates an axial sinusoidal force that can be tuned to a given frequency within a specified operating range when the tubular is clamped or otherwise secured to the oscillator and is thus isolated from the snubbing-type jack when the tubular is released by the jack or tubing injector and suspended by the operator. The axial force generated by the oscillator acts on the tubular extending through the snubbing unit or coiled tubing injector and secured to the oscillator, to create axial vibration of the tubular. When tuned to a resonant frequency of the system, energy developed at the oscillator is efficiently transmitted to the stuck member, with the only losses being those attributed to frictional resistance. The effect of the system reactance is eliminated because mass inductance is equal to spring capacitance at the resonant frequency. The total resonant system is designed such that the components act in concert with one another, thus providing an efficient and effective extraction system.
The principal of resonant axial vibration of pipe and other threaded tubulars can therefore be applied to coiled tubing, as well as threaded tubulars such as casing and drill pipe, using a snubbing-type or load-bearing unit of substantially any design for running the coiled tubing in and out of a well. The combination of a mechanical oscillator and a snubbing-type jack, along with a xe2x80x9cgooseneckxe2x80x9d tubing guide and a coiled tubing injector is highly effective to xe2x80x9crunxe2x80x9d the tubing and to remove stuck coiled tubing from a well, as well as maintaining and enabling good well control, along with the facility for circulating fluids through the coiled tubing into and from the well.
Various pipe recovery techniques are well known in the art. An early pipe recovery device is detailed in U.S. Pat. No. 2,340,959, dated Feb. 8, 1944, to P. E. Harth. The Harth device is characterized by a suitable electrical or mechanical vibrator which is inserted into the pipe to be removed, such that the vibrator may be activated to loosen the pipe downhole in the well and enable removal of the pipe. A well pipe vibrating apparatus is detailed in U.S. Pat. No. 2,641,927, dated Jun. 16, 1953, to D. B. Grabel, et al. The device includes a vibrating element and a motor-powered drive which is inserted in a well pipe to be loosened and removed, to effect vibration of the pipe and subsequent extraction of the pipe from the well. U.S. Pat. No. 2,730,176, dated Jan. 10, 1956, to W. K. J. Herbold, details a means for loosening pipes in underground borings. The apparatus includes a device arranged within a paramagnetic cylindrical body; including a drill, a rod rotatably mounted within the body and a disc member secured to one end of the drill rod, the disc member having a mass which is substantially equally distributed around the axis of the drill rod to define a surface of revolution. A motor is provided for rotating the drill rod and a magnetic apparatus for forcing the disc member into physical contact with the inner walls of the body and into rolling contact with the inner surface of the pipe upon rotation of the drill rod, to loosen the pipe downhole. U.S. Pat. No. 2,972,380, dated Feb. 21, 1961, to A. G. Bodine, Jr., details an acoustic method and apparatus for moving objects held tightly within a surrounding medium. The device includes a vibratory output member of an acoustic wave generator attached to an acoustically-free portion of the stuck tubular. The method includes operating the generator at a resonant frequency to establish a velocity node adjacent to the stuck point and a velocity antinode at the coupling point adjacent to the generator, to loosen the stuck member from the well. U.S. Pat. No. 3,189,106, dated Jun. 15, 1965, to A. G. Bodine, Jr., details a sonic pile driver which utilizes a mechanical oscillator and a pile coupling device for coupling the oscillator body to a pile and applying vibrations of the pile to drive the pile into the ground. U.S. Pat. No. 3,500,908, dated Mar. 17, 1970, to D. S. Barler, details apparatus and method for freeing well pipe. The device includes a number of rotatable, power-driven eccentrics which are connected to an elongated member such as a drill pipe that is stuck in an oil well bore hole and to a resiliently-movable support suspended from the traveling block of an oil derrick. When the power-driven eccentrics are operated, the elongated member is subjected to vertically-directed forces that free it from the stuck position. U.S. Pat. No. 4,429,743, dated Feb. 7, 1984, to Albert G. Bodine, details a well servicing system employing sonic energy transmitted down the pipe string. The sonic energy is generated by an orbiting mass oscillator coupled to a central stem, to which the piston of a cylinder-piston assembly is connected. The cylinder is suspended from a suitable overhead suspension device such as a derrick, with the pipe string being suspended from the piston in an in-line relationship. The fluid in the cylinder affords compliant loading for the piston, while the fluid provides sufficiently high pressure to handle the load of the pipe string and any pulling force thereon. The sonic energy is coupled to the pipe string in the longitudinal vibration mode, which tends to maintain this energy along the string. U.S. Pat. No. 4,574,888 dated Mar. 11, 1986, to Wayne E. Vogen, details a xe2x80x9cMethod and Apparatus For Removing Stuck Portions of A Drill Stringxe2x80x9d. The lower end of an elastic steel column is attached to the upper end of the stuck element and the upper end of the column extends above the top of the well and is attached to a reaction mass lying vertically above, through an accelerometer and vertically-mounted compression springs positioned in parallel with a vertically-mounted, servo-controlled, hydraulic cylinder-piston assembly. Vertical vibration is applied to the upper end of the column to remove the stuck element from the well. A xe2x80x9cDevice For Facilitating the Release of Stuck Drill Collarsxe2x80x9d is detailed in U.S. Pat. No. 4,576,229, dated Mar. 18, 1986, to Robert L. Brown. The device includes a first member mounted with the drill pipe disposed in a first position and a second member concentrically mounted with a drill collar or drill pipes in a second position below the first position. Rotation of the drill string from the surface causes a camming action and vibration in a specified operative position of the device, which helps to free stuck portions of the drill pipe. U.S. Pat. No. 4,788,467, dated Nov. 29, 1988, to E. D. Plambeck details a downhole oil well vibrating apparatus that uses a transducer assembly spring chamber piston and spring to effect vibration of downhole tubulars. U.S. Pat. No. 5,234,056, dated Aug. 10, 1993, to Albert G. Bodine, details a xe2x80x9cSonic Method and Apparatus For Freeing A Stuck Drill Stringxe2x80x9d. The device includes a mechanical oscillator employing unbalanced rotors coupled to the top end of a drill string stuck in a bore hole. Operation of the unbalanced rotors at a selected frequency provides resonant vibration of the drill string to effect a reflected wave at the stuck point, resulting in an increased cyclic force at this point. Patents detailing jacking devices and coiled tubing and other tubular insertion and removal devices, include U.S. Pat. No. 4,465,131, dated Aug. 14, 1984, to Boyadjieff, et al; U.S. Pat. No. 4,585,061, dated Apr. 29, 1986, to Lyons, et al; U.S. Pat. No. 4,655,291, dated Apr. 7, 1987, to Cox; and U.S. Pat. No. 5,566,764, dated Oct. 22, 1996, to Elliston.
The prior art is well established regarding the application of vibration to stuck downhole tubulars of the conventional type (threaded pipe). However, there is no known technique or suggestion of any means or method for handling continuous pipe or tubing such as coiled tubing, in addition to threaded tubulars, using a mechanical oscillator mounted on a snubbing-type jack or lifting mechanism, in a vibrational application. It is therefore an object of this invention to provide an apparatus for working and freeing coiled tubing or other stuck pipe or equipment in a well without using overhead support structure, wherein the tubing or pipe may be vibrated in the well bore by an oscillator mounted on a support structure in vibration-insulated relationship, which support structure includes a tubing or pipe-lifting and lowering apparatus.
Another object of this invention is to provide a new and improved coiled tubing and threaded tubular running and recovery apparatus, including an oscillator having a hollow central stem for receiving the tubular and a snubbing jack in the case of the threaded tubulars, and including a snubbing-type jack or lifting mechanism, a coiled tubing guide and a coiled tubing injector where coiled tubing is used, which apparatus facilitates running, releasing and recovering by vibration, the tubulars and other objects stuck or jammed downhole in a well.
Yet another object of this invention is to provide a new and improved tubing injector with snubbing-type jack or lifting mechanism and oscillator apparatus, which combines a mechanical oscillator having a hollow central stem or tube and clamps for receiving coiled tubing, a coiled tubing guide for guiding the coiled tubing from a reel to the oscillator, a coiled tubing injector for receiving the tubing from the oscillator and running the tubing in a well and a snubbing-type jack for raising and lowering the oscillator, which oscillator is selectively clamped to the coiled tubing and generates a resonant vibration to facilitate the release of stuck or jammed coiled tubing in the well.
Another object of the invention is, to provide a new and improved coiled tubing oscillating/snubbing-type jack or lifting apparatus, including a coiled tubing guide and injector, that may be applied to a continuous length of coiled tubing without cutting the tubing and operated to run, isolate and vibrate the coiled tubing and remove the coiled tubing from a stuck or jammed position in a well.
A still further object of this invention is to provide a new and improved coiled tubing oscillating/snubbing-type jack apparatus for running and freeing tubulars in a well, which apparatus is characterized by a mechanical oscillator, a snubbing-type jack or lifting device located above an injector head seated on the wellhead or other well structure and a coiled tubing guide or xe2x80x9cgooseneckxe2x80x9d positioned above the oscillator and adapted to receive a length of coiled tubing from a reel and direct the coiled tubing through a hollow central stem and a pair of clamps in the oscillator and through the coiled tubing injector head, into and from the well, wherein the oscillator is typically mounted on the snubbing-type jack in vibration-insulated and isolated relationship to facilitate selectively clamping the coiled tubing to the oscillator and thus isolating and vibrating the coiled tubing and removing the coiled tubing from a stuck or jammed condition in the well.
Still another object of this invention is to provide a tubing injector with snubbing-type jack and oscillator apparatus which utilizes a mechanical oscillator mounted on a snubbing-type jack by means of vibration-isolating members and receiving a length of coiled tubing from a reel through a tubing guide for feeding to the coiled tubing injector and isolating the coiled tubing using clamps, applying a resonant vibration directly to the coiled tubing and raising and/or lowering the oscillator by operation of its jack, thus removing the coiled tubing from a stuck or jammed condition in a well.
Another object of this invention is to provide an oscillator/snubbing-type jack apparatus and method of operation, which oscillator is mounted on the snubbing-type jack by means of typically rubber or spring vibration insulators, isolators or reflectors and operates to run threaded tubulars in a well and to release stuck tubulars by vibration. In the case of coiled tubing, the oscillator/snubbing jack combination includes a coiled tubing guide, or xe2x80x9cgooseneckxe2x80x9d and a coiled tubing injector for receiving a length of coiled tubing extending from a coiled tubing reel and directing the coiled tubing through a hollow bore or channel and a pair of clamps in the oscillator and the coiled tubing injector head, into the well, such that the apparatus cap be operated to clamp the coiled tubing, vibrationally isolate and insulate the coiled tubing from the snubbing-type jack and vibrate the coiled tubing, typically at a resonant frequency, and operate the jack apparatus to remove the coiled tubing from a stuck or jammed condition in the well.
Yet another object of the invention is to provide a method of freeing stuck tubulars, including threaded tubulars such as drill pipe and the like, as well as coiled tubing, in a well using an oscillator and snubbing-type jack running and recovery apparatus, which method includes extending the threaded tubular through a pair of clamps and a tubular stem in the oscillator and through the snubbing jack, clamping the tubular in the oscillator, releasing the tubular from the snubbing jack and vibrating the tubular. When coiled tubing is run, the method includes installing a coiled tubing guide above the oscillator for guiding the coiled tubing from a reel through the oscillator, placing a coiled tubing injector beneath the oscillator over the wellhead or structure for receiving and conventionally running the coiled tubing, clamping the coiled tubing in the oscillator and vibrating the coiled tubing to reduce the friction of tubing insertion and extraction in a well while operating the jack.
These and other objects of the invention are provided in a new and improved oscillator and snubbing-type jack tubular recovery apparatus and method of operation, which apparatus is characterized in a first preferred embodiment by a snubbing jack fitted with a mechanical oscillator in vibration-insulating and isolating configuration with respect to the snubbing jack. In another embodiment a coiled tubing guide is added for running coil tubing from a reel to the oscillator, along with a coiled tubing injector for running coiled tubing from the oscillator in the well. The coiled tubing is isolated from the snubbing-type jack by clamping the oscillator to the coiled tubing and releasing the coiled tubing from the snubbing-type jack. The method of this invention includes directing a tubular through a tubular stem in an oscillator mounted on a snubbing jack and, in the case of coiled tubing, from a reel through a coiled tubing guide into the oscillator and then to a coiled tubing injector and into the well bore. In the event of a stuck or jammed condition of the tubular in the well bore, the oscillator is clamped on the tubular and operated to isolate the tubular from the snubbing or snubbing-type jack and apply resonant vibration to the tubular to loosen the tubular in the well bore as the jack apparatus is raised and/or lowered to move the tubular up and/or down in the well.